Nakahara H, Amari S I
Laboratory for Mathematical Neuroscience, RIKEN Brain Science Institute, Wako, Saitama, Japan.
Neural Netw. 2002 Jan;15(1):41-55. doi: 10.1016/s0893-6080(01)00126-5.
The present study investigates the influence of attention modulation on neural tuning functions under a Gaussian correlation structure. Recent experiments have shown that attention modulates the tuning curve via its height and base rate. Inspired by this experimental finding, we previously showed the effective size of attention modulation (i.e. the critical length) on the neural population that enhances encoding accuracy. The previous result, however, was obtained under the assumption of uncorrelated firing, i.e. stimulus-conditional independence of neural responses. A question still remains whether the above findings can be applied to correlated firing. It is important to investigate this issue partly because neural firings are usually correlated but even more so because common attentional inputs may cause correlated firings. The present study first provides the general framework of attention modulation in relation to an attended stimulus and an actual stimulus and then shows the existence of a critical length under a Gaussian correlation structure. In order to improve encoding accuracy, measured by the Fisher information, the height and the base rate should be increased when the attended stimulus is in the critical length from the peak of the tuning curve and decreased otherwise. Furthermore, we confirm that a similar nature of the critical length also holds even when the neural decoder uses an uncorrelated unfaithful model. Thus, the existence of the critical length seems to be a ubiquitous phenomenon in attention modulation, and so its implications are discussed.
本研究调查了在高斯相关结构下注意力调制对神经调谐函数的影响。最近的实验表明，注意力通过其高度和基础速率来调制调谐曲线。受这一实验结果的启发，我们之前展示了注意力调制对神经群体的有效大小（即临界长度），它能提高编码精度。然而，之前的结果是在不相关放电的假设下获得的，即神经反应的刺激条件独立性。一个问题仍然存在，即上述发现是否可以应用于相关放电。研究这个问题很重要，部分原因是神经放电通常是相关的，但更重要的是因为共同的注意力输入可能会导致相关放电。本研究首先提供了与被关注刺激和实际刺激相关的注意力调制的一般框架，然后展示了在高斯相关结构下临界长度的存在。为了提高以费希尔信息衡量的编码精度，当被关注刺激处于从调谐曲线峰值起的临界长度内时，高度和基础速率应增加，否则应降低。此外，我们证实，即使神经解码器使用不相关的非忠实模型，临界长度的类似性质仍然成立。因此，临界长度的存在似乎是注意力调制中一种普遍存在的现象，并对其含义进行了讨论。
